This disclosure relates to articles formed from polyetherimide compositions.
Hydrogen peroxide plasma sterilization devices are known, such as described in U.S. Pat. No. 4,643,876. The article to be sterilized is placed in the plasma chamber, the chamber is closed, and vacuum is drawn on the chamber to remove the gas that is in the chamber. An aqueous solution of hydrogen peroxide is typically injected into the chamber raising the pressure in the chamber to the desired level. The hydrogen peroxide remains in the chamber for a period of sufficient duration to allow the hydrogen peroxide to come in intimate contact with the item to be sterilized, before the plasma is generated at a power level sufficient to achieve sterilization. The power then remains on for the desired period to allow complete sterilization of the particular type of article being treated. As is known to those skilled in the art, the period of treatment will also vary depending upon the concentration of the hydrogen peroxide in the chamber and the amount of power that is applied to the chamber.
Hydrogen peroxide plasma sterilization devices are employed in health care facilities since they provide an easy and cost effective means of sterilizing healthcare devices prior to each use. Hydrogen peroxide plasma sterilization is an alternative to high temperature autoclave sterilization, especially for articles that include sensitive electronic or optical components that cannot be exposed to the high temperatures or moisture of an autoclave without becoming damaged. Hydrogen peroxide plasma sterilization systems operate at lower temperatures than high temperature autoclaves and achieve sterilization of articles through the antimicrobial action of peroxide plasma used instead of extreme temperature. In other instances a hydrogen peroxide vapor, that may contain little or no hydrogen peroxide plasma, may also be used for low temperature sterilization.
However, the adoption of hydrogen peroxide plasma sterilization has placed a new set of durability demands upon materials used to fabricate articles intended for repeated use in a sterile work environment, such as surgical devices of various types and configurations. Improvements in hydrogen peroxide plasma devices have increased the extent of diffusion of peroxide within the chamber, improving the ability to penetrate lumens and broadening the applicability of this technology to a wider range of instruments.
Plastic components that are exposed to repeated hydrogen peroxide plasma sterilizations are thus subjected to repeated rigorous challenges from the action of hydrogen peroxide plasma, an ionized acidic vapor, upon the surface of the molded article and through diffusion below the surface of the article. Retention of properties after exposure to repeated cycles of peroxide plasma sterilization is therefore needed.
There accordingly remains a need in the art for improved sterilized plastic articles that will endure repeated exposures to peroxide plasma sterilization.